With rapid market expansion of laptop computers, mobile phones, electric vehicles, and the like, a secondary battery having a high energy density is required. Examples of a method for obtaining a secondary battery having a high energy density include a method in which an anode material having large capacity is used, and a method in which a nonaqueous electrolytic solution having a superior stability is used.
Patent document 1 discloses using silicon oxide or a silicate as an anode active material of a secondary battery. Patent document 2 discloses an anode for a secondary battery which has an active material layer containing a particle of carbon material that can absorb and desorb a lithium ion, a metal particle that can be alloyed with lithium, and an oxide particle that can absorb and desorb a lithium ion. Patent documents 3 discloses an anode material for a secondary battery which is formed by coating a surface of a particle, which has a structure in which silicon fine crystal is dispersed in a silicon compound, with carbon.
Patent document 4 discloses a nonaqueous electrolytic solution which contains a fluorine-containing phosphoric acid ester having the following structure:
In the formula, Rf1, Rf2 and Rf3 are identical or different and are each a fluorine-containing alkyl group having a carbon number of 1 to 3.
Patent document 5 and Patent document 6 disclose using a polyimide as an anode binder when an anode active material contains silicon.